Compact tool message history responses

[piorpua]

Summary

• Add compact history response mode for oversized tool messages.
• Add a full single-message endpoint for lazy detail loading.
• Log compact-list and full-detail metadata for production diagnosis.

Test Plan

• cargo fmt --all -- --check
• cargo clippy -p aionui-conversation -p aionui-app -- -D warnings
• cargo test -p aionui-conversation t8_6_compact_mode_truncates_large_tool_content_only_for_list_response -- --nocapture
• cargo test -p aionui-app t8_2 --test message_e2e -- --nocapture
• just push -u origin feat/tool-message-compact